Apparatus for recording CT images directly on a recording medium without using a CRT

ABSTRACT

A medical image recording apparatus according to the present invention in which the optical path length of the optical system is extremely short and the number of mechanical operating mechanisms is reduced electronically scans an LED array assembly (14) having a plurality of one-dimensionally arranged LED&#39;s with an LED array controller (28) and feeds a photosensitive recording medium (15) in a direction perpendicular to the direction of arrangement of the LED&#39;s by means of a motor (17) controlled by a film feed controller (29). The LED array controller and the film feed controller are operated on the basis of commands given from a scanning controller (27) which is controlled by a CPU. The quantity of light emitted from each individual LED in the LED array assembly is controlled in accordance with a signal given to the LED array controller, the signal being formed in such a manner that image data which is stored in an image data storing memory (22) through an input interface (21) is formatted by means of an image formatter (25) and then converted into an analog signal by means of a D/A converter (26) or a pulse-width modulation circuit (30).

TECHNICAL FIELD

The present invention relates to a medical image recording apparatus forrecording images output from various kinds of diagnostic system such asan X-ray CT. More particularly, the present invention pertains to amedical image recording apparatus which effects recording directly on arecording medium without using a CRT and in which the optical pathlength of the optical system is extremely short and the number ofmechanical operating mechanisms is reduced.

BACKGROUND ART

It is conventional practice to display an image obtained by an X-ray CTor the like on the screen of a CRT and record the displayed image bymeans of a multiframe photographic recording apparatus. This methodinvolves problems in terms of, for example, resolving power, imagedistortion and fluorescent noise, since the CRT is employed as a medium.For this reason, medical image recording apparatuses which are arrangedto record an image directly on a silver halide film by means of a laserbeam scanning system have appeared. Unlike the conventional type ofapparatus in which the image displayed on a CRT is recorded on a film(referring to silver halide photosensitive materials includingphotographic paper in this specification), this new type of apparatus isdesigned to record an image directly on a film by means of a laser beamwhich has been subjected to analog modulation.

FIG. 3 shows one example of the basic arrangement of this type ofmedical image recording apparatus. The reference numeral 1 denotes aHe-Ne laser, 2 a lens, and 3 a prism. Light which is emitted from thelaser 1 is passed through the lens 2 and bent 90° by the prism 3 beforeentering an acoustooptic modulator 4, where the laser light is modulatedby an ultrasonic wave modulated by information concerning the light andshade of an image so as to form light which carries informationconcerning the light and shade of the image. This light is then passedthrough a beam expander 5 and a prism 6 to enter a polygon mirrorscanner 8 after the toppling angle has been corrected by a topplingangle correcting optical system 7. The polygon mirror scanner 8 isarranged such that a mirror is rotated and incident light is reflectedby the rotating mirror so as to scan a recording film 9 laterally inorder to record an image on the film 9. On the other hand, longitudinalscanning is effected by feeding the film 9 through a film feed mechanism10.

The above-described medical image recording apparatus has advantagessuch as excellent resolving power, less image distortion and nofluorescent noise since it does not employ a CRT as a medium.

This medical image recording apparatus suffers, however, from thefollowing problems. As will be clear from FIG. 3, the apparatus usesmechanical scanning mechanisms for main and subsidiary scanningoperations, that is, the mechanism for rotating the polygon mirrorscanner 8 for effecting abscissa scanning as main scanning and therecording film feed mechanism for effecting subsidiary scanning.Therefore, the number of movable portions is relatively large, which isdisadvantageous in terms of reliability and transport durability.Further, the optical path length from the laser light source to the filmis considerably long, so that it is difficult to arrange the apparatusso as to have a compact structure even though the mirrors are used tobend the beam in order to prevent the optical path from elongating inone direction.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to realize a compact medicalimage recording apparatus by reducing the number of movable portions andshortening the optical path length.

In the medical image recording apparatus according to the presentinvention, an LED array assembly (14) having a plurality ofone-dimensionally arranged LED's is electronically scanned with an LEDarray controller (28), and a photosensitive recording medium (15) is fedin a direction perpendicular to the direction of arrangement of theLED's by means of a motor (17) which is controlled by a film feedcontroller (29). The LED array controller and the film feed controllerare operated on the basis of commands given from a scanning controller(27) which is controlled by a CPU. The quantity of light emitted fromeach individual LED in the LED array assembly is controlled inaccordance with a signal given to the LED array controller, the signalbeing formed in such a manner that image data which is stored in animage data storing memory (22) through an input interface (21) isformatted by means of an image formatter (25) and then converted into ananalog signal by means of a D/A converter (26) or a pulse-widthmodulation circuit (30).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a recording mechanism portion of a medicalimage recording apparatus in accordance with one embodiment of thepresent invention;

FIG. 2 is a block diagram of a control system employed in the medicalimage recording apparatus according to the present invention;

FIG. 3 is a schematic view of a conventional medical image recordingapparatus;

FIG. 4 shows one example in which two LED arrays are employed; and

FIG. 5 is a block diagram of a control system in accordance with anotherembodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described hereinunder indetail with reference to the drawings.

FIG. 1 is a schematic view of a recording mechanism portion of a medicalimage recording apparatus in accordance with one embodiment of thepresent invention, and FIG. 2 is a block diagram of a control systememployed in the medical image recording apparatus according to theembodiment of the present invention. The operation of the control systemwill first be explained with reference to FIG. 2. Image data which is aninput signal to the medical image recording apparatus is stored in animage data storing memory 22 through an input interface 21. Fetching ofthe image data into the input interface 21 is controlled by a CPU 24 inaccordance with a command which is given from a camera operationcontroller 23. The image data stored in the image data storing memory 22is delivered to a D/A converter 26 in accordance with a sequenceconstructed by a image formatter 25 in accordance with a recordingformat (frame layout) command which is given from the CPU 24 on thebasis of a command issued from the camera operation controller 23, andthe image data is then converted into an analog signal in the converter26. At the same time, the recording format command from the CPU 24 isalso given to a scanning controller 27 so as to give command signals toan LED array controller 28 and a film feed controller 29, thscontrolling a motor 17 and an LED array assembly 14 so that scanning inx- and y-directions is carried out. On the other hand, the analog datasignal from the D/A converter 26 is supplied to the LED array controller28 in order to control the LED array assembly 14. In this case, both ofthem are operated on the basis of the recording format command issuedfrom the CPU 24 and therefore of course, synchronized with each other.

FIG. 5 shows another example of this circuit. In FIG. 5, the referencenumeral 30 denotes a pulse-width modulation circuit which converts imagedata into a pulse-width modulation signal and supplies this signal tothe LED array controller 28. The other members or portions of thisarrangement are similar to those shown in FIG. 2.

Referring next to FIG. 1, the LED array assembly 14 comprises an LEDarray 11, an LED driving IC 12 and a rod lens array 13. The LED array 11performs exposure by means of light emitted from LED elements arrangedat a high density (e.g., 16 dots/mm) in such a way that an image isformed on a film 15 through the rod lens array 13. In this case, thefilm 15 and the rod lens array 13 are not in contact with each otheralthough they are in close proximity with each other. The scanning inthe x-direction is effected in accordance with a command from the LEDarray controller 28 on the basis of a command issued from the scanningcontroller 27, and the emission of light from the elements of the LEDarray 11 is effected by the operation of the LED driving IC 12 on thebasis of a command from the LED array controller 28 which is, in turn,based on data supplied from the D/A converter 26. The time required forscanning in the x-direction can be shortened by simultaneously turningon a plurality of LED elements. The quantity of light emitted from eachLED element is controlled in an analog manner by means, for example, ofdirect modulation or pulse-width modulation of the driving current. TheLED arra controller 28 modulates the quantity of light emitted from eachLED element on the basis of an analog data signal and also performscontrol of switching with respect to the LED elements and compensationfor luminance differences between the elements due to variations incharacteristics.

Scanning in the y-direction, that is, the feed of the film, is effectedby rotating a film feed roller 16 in accordance with the command givento the motor 17 from the film feed controller 29. It should be notedthat the film feed controller 29 also performs unloading of a film froma supply magazine (not shown) and setting of the film, or loading of arecorded film ino a receive magazine (not shown).

As will be clear from the above-described structure and operation, inthe medical image recording apparatus according to the presentinvention, the optical path of the exposure mechanism is extremelyshort, and the scanning in the x-direction is effected electricallyalthough the scanning in the y-direction is mechanically carried out.Thus, only one mechanical means is used and the number of movableportions is reduced.

It should be noted that the above-described elements are merelyexamples. For example, although the input interface in the abovedescription is a digital element, a video interface may be provided withrespect to the input of an analog video signal and the signal may bedigitalized by means of an A/D converter and stored in the image datastoring memory. Although in the above-described embodiments the scanningin the y-direction is effected by feeding the film, the LED array may bemoved to effect scanning in the y-direction. Further, although in theabove-described embodiments the LED array is a single array whichextends over the width of a film, two arrays may be arranged in two rowsas shown in FIG. 4 in order to reduce the length of a row of LEDelements for one array. In such a case, the LED arrays are, of course,controlled such that, at the central overlapping portion, either one ofthe arrays alone is turned on.

As has been described above in detail, it is possible, according to thepresent invention, to obtain a medical image recording apparatus inwhich the optical path length is extremely short and the number ofmovable portions is reduced and which is therefore improved inreliability and maintainability.

Although the present invention has been described above by way of thebest mode for carrying out it, it will be easy for those who haveordinary knowledge of the technical field to which the present inventionbelongs to make various modifications without departing from the scopeof the following claims.

We claim:
 1. A CT medical image recording apparatus comprisinga centralprocessing unit; a camera operation controller; an LED array assemblyhaving an LED array defined by a plurality of LEDs arranged in a linedefined in an X direction; an LED array array controller for controllingthe emission of light from each of said LEDs constituting said LED arrayin said LED array assembly; mechanical feed means for moving a flatplanar photosensitive recording medium in a Y direction substantiallyperpendicular to said X direction of said LED array, said recordingmedium being selectively irradiated with light from selected ones ofsaid plurality of LEDs of said LED array; a feed controller connected tosaid mechanical feed means for controlling said mechanical feed means; ascanning controller connected to said central processing unit, said feedcontroller and said LED array controller and responsive to signals fromsaid central processing unit based on command from said camera operationcontroller for concurrently controlling both said LED array controllerto provide selective electronic X direction scanning of said recordingmedium by said LED array and said feed controller to provide mechanicalY direction scanning of said recording medium by said mechanical feedmeans; an interface connected to said central processing unit foraccepting input image data; image data storing means connected to saidinterface and to said central processing unit for effecting formattingusing a recording format provided by said central processing unit basedon a command from said camera operation controller, said format beingused for image recording with respect to image data read out from saidimage data storing means; and emitted light quantity modulating meansconnected to said image data storage means and to said LED arraycontroller for supplying to said LED array controller a signal whichmodulates the quantity of light emitted from each of said LEDsconstituting said LED array on the basis of said image data which isformatted by said image formatter.
 2. A medical image recordingapparatus according to claim 1, wherein said mechanical feed meanscomprises means for moving said photosensitive recording medium.
 3. Amedical image recording apparatus according to claim 1, wherein saidmechanical feed means comprises means for moving said LED arrayassembly.
 4. A medical image recording apparatus according to claim 1,wherein said interface for input image data is an interface for adigital signal.
 5. A medical image recording apparatus according toclaim 1, wherein said interface for input image data is an interface foran analog signal.
 6. A medical image recording apparatus according toclaim 1, wherein said emitted light quantity modulating means includes aD/A converter.
 7. A medical image recording apparatus according to claim1, wherein said emitted light quantity modulating means includes apulse-width modulation circuit.